According to the immune surveillance hypothesis, the immune system is continuously sensitized against developing tumours, where experimental evidence strongly supports this notion. The identification of specific tumour antigens has created new possibilities for tumour immunotherapy and many immunotherapeutic approaches are now being translated into clinical trials. Among these, adoptive transfer of tumour antigen-specific lymphocytes seems particularly promising. These attempts have, so far, usually been based on either mononuclear cells from peripheral blood or tumour infiltrating lymphocytes (TIL) separated from fresh tumour specimens. In recent trials, treatment of patients with malignant melanoma with autologous transfer of expanded TILs, objective response rates of up to 51% has been reported. TIL cells are few, they are frequently unresponsive (anergic) due to immunosuppressive mechanisms from the tumour creating long periods for expansions to occur (several months). Furthermore, the protocols have been aiming towards the expansion of CD8+ cytotoxic T cells and the cells have been reintroduced into patients preconditioned with chemotherapy and in addition the patients have been treated with high doses of interleukin-2 to provide survival of CD8+ T cells.